Back-rest for dental chairs.



No. 694,683. Patented Mar. 4, I902.

G. SIBLEY. BACK BEST FOR DENTAL CHAIRS.

(Application filed May 29, 1900.)

(No Model.)

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UNITED STATES PATENT ()FFICE.

G IDEON SIBLEY, OFPHILADELPHIA, PENNSYLVANIA.

BACK-REST FOR- DENTAL CHAIRS.

SPECIFICATION forming part of Letters Patent No. 694,683, dated March 4,1902.

Application filed May 29, 1900.

T0 on whom it may concern:

Be it known that I, GIDEONSIBLEY, a citizen of theUnited States,residing inthecity; and county of Philadelphia and State of Pe'nn-.sylvania, have invented certain new and useful Improvements in BackRests for Dental Chairs, of which the following is a full, clear, andexact description, reference being had to the accompanying drawings,forming a part of this specification.

This invention relates to the back-rests of dental and other chairs, myobject herein being to provide, first, a simple and efficient meanswhereby the back-frame may be locked in different positions of angularadjustment in respect to the seat-section, and, secondly, an improvedconstruction whereby the backslide may be locked in predeterminedpositions of longitudinal adjustment on said frame, as will behereinafter described and claimed.

In the drawings, Figure 1 is a sectional side elevation of a portion ofa chair embodying my invention. Fig. 2 is a front elevation, partiallyin section, of the back-frame, its supporting-bars, and the lockingdevices, the back-rest proper being removed. Fig. 3 is a transversesection enlarged as on the line 8 3- of Fig. 2. Fig. 4 is a similarsection as on the line 4. 4 of Fig. 1 g

A is the seat-base; B, the back-frame; O, the back-slide, and D the restor cushion. The back-frame is provided at its lower end with laterallugs 19, which'are hingedly connected with lugs a on the seat-base, sothat the said frame,withits appurtenances, may be swung backward andforward, as desired. Pivoted to the rear of the said base are the. lowerends of two bars 5' 19 which extending freely into longitudinal pocketsor guideways b in the back-frame permit the adjustment. of the latter,yet upon the clamping together of thebars and frame sustain the frame ata predetermined position of angular adj ustment in respect to theseat-section.

At the lower end of the back-frame in. the space between the bars b bare affiXed two parallel studs e e, on one of which is very looselymounted a roller E, that'takes against the opposing edges of theadjacent bar b, while on the other stud is likewise loosely mounted acam E,which acts upon said roller Serial No. 18,366. (No model.)

and upon the opposing edge of the bar 19 (See Fig. 3.) Formed on oraffixed to this cam is a laterallyextending arm 6 which passes throughan aperture 6 in the backframe and'is pivotally connected with a collare on a verticallymovable rod e fitted within said frame. This rod isprovided at its respective ends with eXteriorly-projecting knobs e bymeans of which the rod may be manipulated. Encircling the rod is aspring e which bearing upon the collar 6 and a shoulder a in the frametends to maintain the rod normally depressed. The construction of thecam is such that when the rod is thus depressed the cam bears againstthe bar b and presses the roller against the bar I),

requisite adjustment of the back-frame When the rod is released, the camand roller automatically resume"their normal position to insure theclamping of the back-frame in place,

.The slide 0 is fitted to longitudinal guideways Win the back-frame, soas to be movable up'and down therein, and it is provided with aprojection c, which extends through a longitudinal slot 19 in saidframe. Pivoted to this projection is a cam-lever F, the cam portion f ofwhich embraces the outer end of the projection and acts against theback-frame, so that the weight of the latter tends to turn the .cam, andthus effect the clam'pin g of the slide in a predetermined position'ofvertical adjustment on said frame. On the lever is a lugf, against whichbears theouter end of a spring f seated in a socket in the projection,the pressure of the spring tending to maintain the cam-lever normally inclamping position. B y slightly raising the arm of the lever against thestress of the springthe slide is unclamped to permit the requisiteadjustment thereof.

Upon the release of the lever it will automat ically resume its normalposition to effect the clamping of the slide in the desired position ofadjustment.

The cushion or rest D is pivoted at or near its upper end to the slideas usual, so that it may be swung to and from the same, and is providedwith a dog or dogs (Z, adapted to 00- act with a rack or racks d on saidslide for the purpose of supporting the cushion or rest at the properangle with respect to the slide.

I claim 1. In a chair, the combination with the seat and the swingingback-frame, of the supporting-bar extending into said frame, a device insaid frame movable against the bar, a cam in said frame adapted to actupon said device to clamp it against the bar, said device beinginterposed between the cam and the Wall of said frame, and means foroperating said cam, substantially as described.

2. In achair, the combination with the seat and the swinging back-frame,of the supporting-bar extending into said frame, a device in said framemovable against the bar, a camin said frame adapted to act upon saiddevice to clamp it against the bar, and means for maintaining said camnormally in contact with said device, substantially as described.

3. In a chair, the combination with the seat and the swingingback-frame, of the supporting-bar extending into said frame, a roller insaid frame adapted to coact with said bar, a cam in said frame adaptedto act upon said roller to clamp it against the bar, and means foroperating said cam, substantially as described.

4. In a chair, the combination with the seat and the swingingback-frame, of the supporting-bars extending into said frame, thecoacting roller and cam engaging the respective bars, and means foroperating said cam, substantially as described.

5. In a chair, the combination with the seat and the swingingback-frame, of the supporting-bars extending into said frame, thecoacting roller and cam engaging the respective bars, and means formaintaining said cam and roller normally in contact with each other andwith said bars, substantially as described.

6. In a chair, the combination with the seat and the swingingback-frame, of the supportin g-bars extending into said frame, theparallel studs affixed to said frames between the bars, a roller and acam loosely mounted on the respective studs, and means whereby said camand roller are normally maintained in contact with each other and withthe respective bars, substantially as described.

7. In a chair, the combination with the seat and the swingingback-frame, of the supporting-bars extending into said frame, theparallel studs affixed to said frame between the bars, a roller and acam loosely mounted on the respective studs, an arm on said cam, a rodconnected therewith, and a spring acting upon said rod to maintain thesame normally in such position that the said roller and cam are heldyieldingly in contact wit-h each other and with the respective bars,substantially as described.

8. In a chair, the combination with the backframe, and the slidethereon, of the cam-lever mounted on said slide, means whereby thecam-head of the lever is maintained normally in contact with said frame,and means exteriorly of the frame for operating said camlever,substantially as described.

9. In a chair, the combination with the longitudinally-slottedback-frame and the slide thereon provided with a projection extendingthrough the slot in said back, of the cam-lever fulcrumed on saidprojection, and a spring tending normally to maintain said lever incontact with the frame, substantially as described.

In testimony whereof I have hereunto affixed my signature in thepresence of two subscribing witnesses.

GIDEON SIBLEY.

Witnesses:

N. S. BUCKINGHAM, ANDREW V. GROUPE.

